If you were betting on the NFL last weekend, there's a good chance that you ended the weekend with a pretty serious headache. Chicago, Atlanta and Minnesota seemed to many to be among the safest bets on the week, yet they all managed to lose as favorites, falling to Miami, Detroit and San Francisco, respectively. In each case the losses were fairly ugly, and each game probably has to somewhat change our perceptions of each team involved. It's another confusing situation in a season that has found all sorts of ways to confuse us thus far. Here's a look at the lessons that emerge from each of those games:

Miami at Chicago - Chicago had looked unbeatable and Miami had struggled. Despite a 13.5-point spread, commentators were tripping over each other coming up with ways to explain just how sure they were of a Chicago victory. It was an undefeated team at home playing in November against a cold weather team - what could possibly go wrong? Pretty much everything, as it turns out.

The most obvious concern Chicago has to have is at quarterback. Up until this game Rex Grossman was looking like a star and people were already assigning him a locker at the Pro Bowl. People will want to hold off on that notion until further notice. His numbers, 18-of-42 for 210 yards with a touchdown and three interceptions is pretty pathetic, and it gets even worse when you add in the lost fumble, too. This performance is concerning, but not unique. Grossman has had three off games this season, and the Bears have come close to losing all three of them. A late touchdown pass to take the lead took some of the heat off his weak performance against Minnesota. He threw four interceptions and fumbled twice against Arizona in the miraculous comeback game that Chicago really had no business winning.

The Bears obviously need Grossman to play well to win. Decisions about how to play the Bears, then, will depend on how you feel Grossman is going to perform. It has to be of particular concern that Grossman's two worst performances, against Miami and Arizona, came within the last three games.

Another concern for Chicago is their suddenly disappearing run defense. Ronnie Brown ran for 157 yards and averaged 5.4 yards per carry. He was running at will, and a championship team can't let that happen. For the most part the run defense of the Bears has been good, but there have been problems. Ahman Green scampered for 110 yards in the season opener and Frank Gore put up 111 yards two weeks ago. The fact that backs have put up big numbers two weeks in a row has to be addressed.

The pass defense was less scary. They allowed Joey Harrington to throw a very un-Harrington-like three touchdowns, but he also put up some more typical stats - two interceptions and 50 percent completion rates.

The lesson from both teams is the same - they aren't what they may have appeared. The Bears had looked like the best team in the league, but there are some serious reasons to doubt them. The Dolphins looked like world killers in Chicago, but they haven't proven that's what they are yet. I won't be in a big hurry to back either team for a while.

Minnesota at San Francisco - The Vikings have put up a total of 10 points in two straight terrible losses. They didn't look like they belonged on the same field as the Patriots, and they never looked like they even bothered to take the field against the Niners. Brad Johnson has long been a solid reliable veteran that doesn't make mistakes, but the last two weeks he has just looked old. He's still completing 64 percent of his passes, but he has four interceptions and no touchdowns in two weeks, and most of the picks have looked terrible.

The timing of Minnesota's collapse makes no sense. They came off a bye week to completely annihilate the Seahawks in every aspect of the game and Brad Johnson played well. You would think that would be a foundation to build a streak on, but then came the two completely lacking efforts. It's a new coaching staff, and last week's game really makes you wonder how well they are being listened to. The loss to the Patriots would be hard to take, but a well-coached team with any pride should have bounced back from that, especially against the Niners. They'll have to show they care before they warrant a pick to win.

The Niners are an oddity. They have allowed more points than anyone, their offense is showing potential but not realizing it consistently, and they have had some truly humiliating performances, yet they have still managed to win three games, and to cover four of eight. They are the true nightmare for bettors - a completely unpredictable team.

Atlanta at Detroit - Any reports that Michael Vick had turned into a well-rounded quarterback were obviously premature. There has been a passing element in his game that we haven't seen before, but he can clearly be knocked off that game when an opposing defense is in top form. Against the Lions he was 17-of-32 for just 163 yards, with a touchdown and two interceptions, and he lost a fumble. The Lions were able to keep him off balance, to consistently cover his receivers and to pass rush as effectively as you can against Vick.

Detroit even managed to keep the run more in check than most have against the Falcons. They still managed a total of 165 yards, but outside of a big run by Vick and one by Warrick Dunn, most of that yardage was in small bits and was reasonably harmless.

For Atlanta, this performance raises the same concerns I have always had about the Falcons, and about Vick - there is a tremendous amount of talent, but the application of that talent is very inconsistent. Until they decide that they actually want to be a very good team they will be worth attention in certain spots as a play, but they won't warrant consistent consideration.

For the pitiful Lions, the last five weeks has to signify some hope. They have won and covered twice, and they have been within just five points combined of covering the other three games. Rod Marinelli has the makings of a good coach and he might actually almost have this train wreck back on the tracks.